Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Harnessing adaptive capacity to close the pandora’s box of open innovation
    Mahdad, Maral ; Marco, Chiara Eleonora De; Piccaluga, Andrea ; Minin, Alberto Di - \ 2020
    Industry and Innovation 27 (2020)3. - ISSN 1366-2716 - 264 p.
    This paper focuses on how companies deploy structural properties of adaptive capacity (multiplexity, redundancy and loose coupling) to cope with the phenomenon of internal challenges of Open Innovation (OI) implementation, i.e. organisational and cultural changes. We developed a single case study, which offered significant findings. First, the multiplexity of relationships in OI settings helps to face the challenges of organisational and cultural changes by triggering trust formation and interaction. Second, redundancy has twofold elements: institutional logics redundancy triggers cultural change challenges which can be overcome through management practices and communications; task redundancy facilitates knowledge sharing and collaboration, thus helping to deal with organisational change challenges. Finally, loose coupling in OI settings facilitates social interconnectedness among members through management practices, helping to face organisational and cultural change challenges. We provide managerial and theoretical implication to deal with the challenges of OI in relation to both organisational and cultural changes.
    Evolution of Plant Hormone Response Pathways
    Blaacutezquez, Miguel A. ; Nelson, David C. ; Weijers, Dolf - \ 2020
    Annual Review of Plant Biology 71 (2020). - ISSN 1543-5008 - p. 327 - 353.

    This review focuses on the evolution of plant hormone signaling pathways. Like the chemical nature of the hormones themselves, the signaling pathways are diverse. Therefore, we focus on a group of hormones whose primary perception mechanism involves an Skp1/Cullin/F-box-type ubiquitin ligase: auxin, jasmonic acid, gibberellic acid, and strigolactone. We begin with a comparison of the core signaling pathways of these four hormones, which have been established through studies conducted in model organisms in the Angiosperms. With the advent of next-generation sequencing and advanced tools for genetic manipulation, the door to understanding the origins of hormone signaling mechanisms in plants beyond these few model systems has opened. For example, in-depth phylogenetic analyses of hormone signaling components are now being complemented by genetic studies in early diverging land plants. Here we discuss recent investigations of how basal land plants make and sense hormones. Finally, we propose connections between the emergence of hormone signaling complexity and major developmental transitions in plant evolution.

    Impact of post-ruminally infused macronutrients on bovine mammary gland expression of genes involved in fatty acid synthesis, energy metabolism, and protein synthesis measured in RNA isolated from milk fat
    Nichols, Kelly ; Bannink, André ; Baal, Jurgen Van; Dijkstra, Jan - \ 2020
    Journal of Animal Science and Biotechnology 11 (2020)1. - ISSN 1674-9782
    Cytoplasmic crescent - Endoplasmic reticulum biogenesis - Mammary cell - Milk fat globule - Milk synthesis - Tricarboxylic acid cycle

    Background: Characterising the regulation of milk component synthesis in response to macronutrient supply is critical for understanding the implications of nutritional interventions on milk production. Gene expression in mammary gland secretory cells was measured using RNA isolated from milk fat globules from 6 Holstein-Friesian cows receiving 5-d abomasal infusions of saline, essential amino acids (AA), or glucose (GG) or palm olein (LG) without (LAA) or with (HAA) essential AA, according to a 6 × 6 Latin square design. RNA was isolated from milk fat samples collected on d 5 of infusion and subjected to real-time quantitative PCR. We hypothesised that mRNA expression of genes involved in de novo milk fatty acid (FA) synthesis would be differently affected by GG and LG, and that expression of genes regulating transfer of tricarboxylic acid cycle intermediates would increase at the HAA level. We also hypothesised that the HAA level would affect genes regulating endoplasmic reticulum (ER) homeostasis but would not affect genes related to the mechanistic target of rapamycin complex 1 (mTORC1) or the integrated stress response (ISR) network. Results: Infusion of GG did not affect de novo milk FA yield but decreased expression of FA synthase (FASN). Infusion of LG decreased de novo FA yield and tended to decrease expression of acetyl-CoA carboxylase 1 (ACC1). The HAA level increased both de novo FA yield and expression of ACC1, and tended to decrease expression of mitochondrial phosphoenolpyruvate carboxykinase (PCK2). mRNA expression of mTORC1 signaling participants was not affected by GG, LG, or AA level. Expression of the ϵ subunit of the ISR constituent eukaryotic translation initiation factor 2B (EIF2B5) tended to increase at the HAA level, but only in the presence of LG. X-box binding protein 1 (XBP1) mRNA was activated in response to LG and the HAA level. Conclusions: Results show that expression of genes involved in de novo FA synthesis responded to glucogenic, lipogenic, and aminogenic substrates, whereas genes regulating intermediate flux through the tricarboxylic acid cycle were not majorly affected. Results also suggest that after 5 d of AA supplementation, milk protein synthesis is supported by enhanced ER biogenesis instead of signaling through the mTORC1 or ISR networks.

    Soil Microbial Communities on the anode and 2-m distance of Tubular Plant Microbial Fuel Cell in a Paddy Field in West Kalimantan, Indonesia
    Sudirjo, Emilius ; Jager, Pim de; Buisman, Cees ; Strik, David - \ 2020
    Wageningen University
    PRJEB34787 - ERP117748 - metagenome - Plant Microbial Fuel Cell - Soil Microbial Communities - Paddy Field
    Soil samples were collected (on 30 June 2018) from 6 different locations for microbial community analysis from a paddy field in West Kalimantan, Indonesia (0.919215N, 109.468182E; elevation 100m above sea level). Sample A: Soil that attached on the anode from mid of Plant-MFC 1Sample B: soil that attached on the anode from end of the plant-MFC 1Sample C: Soil that attached on the anode from mid of Plant-MFC 2Sample D: soil that attached on the anode from end of the plant-MFC 2Sample E: soil from 2 m distance at northen side of plant-MFC 1 & 2Sample F: soil from 2 m distance at southern side of plant-MFC 1 & 2Samples were grouped into 3: Group I (Samples A and C) was soil that attached on the anode from mid plant-MFC; Group II (samples B and D) was soil that attached on the anode from end of the plant-MFC; and Group III (samples E and F) was from soil with 2 m distance from plant-MFC 1 and 2. After collection, samples were kept in a 30ml-tube container and keep in 40C fridge. The next day samples were transported for 48hours with a cool-ice box for DNA extraction to Genetika Lab, Jakarta (PT. Genetika Science Indonesia), a partner company from 1st BASE Axil Scientific Pte Ltd, Singapore. Sequencing steps were performed by 1st BASEas following: the universal primers that targeted the V3V4 regions were used for amplification. The quantity and quality of the PCR product that targeted the V3V4 regions were measured using Tapestation 4200, picogreen and nanodrop. All the samples passed the QC measurement and proceed straight for a library preparation. The libraries were prepared using Illumina 16s metagenomics library prep kit and their quality and quantity were determine using Agilent Tapestation 4200, Picogreen and qPCR. These libraries were then pooled according to the protocol recommended by the Illumina and proceed straight to sequencing using MiSeq platform at 2x301PE format by 1st BASE Axil Scientific Pte Ltd, Singapore.
    Experimental bottom trawling finds resilience in large-bodied infauna but vulnerability for epifauna and juveniles in the Frisian Front
    Tiano, Justin C. ; Reijden, Karin J. van der; O'Flynn, Sarah ; Beauchard, Olivier ; Ree, Sietse van der; Wees, Jelmer van der; Ysebaert, Tom ; Soetaert, Karline - \ 2020
    Marine Environmental Research 159 (2020). - ISSN 0141-1136
    Beam trawling - Benthic ecology - Biodiversity - Pulse trawling - Sediment profile imagery - Side-scan sonar - Underwater video

    In this study, we analysed the benthic effects of two in situ fisheries disturbance experiments using a combination of side-scan sonar, high definition underwater video, sediment profile imagery, and box core sampling techniques after conventional beam trawling and box core sampling after electric pulse trawling in a southern North Sea habitat. Acoustic and optical methods visualised the morphological changes induced by experimental beam trawling, showing the flattening and homogenisation of surface sediments. Video transects found a 94% decrease in epibenthos in beam trawled sediments compared to an untrawled control site and a 74% decrease in untrawled sediments of the same transect. Box core samples taken 5.5 h, 29 h and 75 h after trawling detected a downward trend in infaunal densities and species richness that continued after the initial impact with small-bodied and juvenile taxa being especially prone to depletion. Data from shallow sediment samples showed trawl resilience in large mud shrimps and evidence of their upward movement towards the sediment surface after disturbance. Both trawl gears induced significant changes to infaunal communities, with no differential effect between the two gears. Our results suggest that in the Frisian Front, trawling may favour the survival of deep burrowers while removing surficial macrofauna.

    Co-optimization of safety, quality and legislation: opening Pandora’s box?
    Boekel, M.A.J.S. van; Steeg, P.F. ter; Dahoe, A.E. - \ 2020
    Current Opinion in Food Science 35 (2020). - ISSN 2214-7993 - p. 65 - 71.
    Current scientific practices and legal reality are discussed related to process modeling of food quality. Historically, microbial safety was the focus, using simple first-order kinetics, known as the D-z concept. The impressive safety record of heated processed foods made this the standard in every food engineering textbook, and adopted by food safety authorities. However, procedures are empirically adjusted to prevent spoilage and extend shelf life. Points of criticism are: i) more advanced models and computational methods allow for better optimization, ii) too strong a focus on fitting experimental results rather than on predictive power of models, iii) choice of process targets and emerging targets, iv) new preservation technologies have a hard time to prove themselves when heating remains the legal bench mark, v) nutritional value, organoleptic properties, sustainability demand more attention nowadays. In conclusion, models for co-optimization of relevant quality attributes should become the focus rather than only safety; legal rules should be revisited.
    Linking the morphology and ecology of subtidal soft-bottom marine benthic habitats: A novel multiscale approach
    Mestdagh, Sebastiaan ; Amiri-Simkooei, Alireza ; Reijden, Karin J. van der; Koop, Leo ; O'Flynn, Sarah ; Snellen, Mirjam ; Sluis, Christiaan Van; Govers, Laura L. ; Simons, Dick G. ; Herman, Peter M.J. ; Olff, Han ; Ysebaert, Tom - \ 2020
    Estuarine Coastal and Shelf Science 238 (2020). - ISSN 0272-7714
    Macrobenthos - Multibeam sonar - Sand waves - Sandbanks - Seafloor morphology - Video transect

    High-resolution surveying techniques of subtidal soft-bottom seafloor habitats show higher small-scale variation in topography and sediment type than previously thought, but the ecological relevance of this variation remains unclear. In addition, high-resolution surveys of benthic fauna show a large spatial variability in community composition, but this has yet poorly been linked to seafloor morphology and sediment composition. For instance, on soft-bottom coastal shelves, hydrodynamic forces from winds and tidal currents can cause nested multiscale morphological features ranging from metre-scale (mega)ripples, to sand waves and kilometre-scale linear sandbanks. This multiscale habitat heterogeneity is generally disregarded in the ecological assessments of benthic habitats. We therefore developed and tested a novel multiscale assessment toolbox that combines standard bathymetry, multibeam backscatter classification, video surveying of epibenthos and box core samples of sediment and macrobenthos. In a study on the Brown Bank, a sandbank in the southern North Sea, we found that these methods are greatly complementary and allow for more detail in the interpretation of benthic surveys. Acoustic and video data characterised the seafloor surface and subsurface, and macrobenthos communities were found to be structured by both sandbank and sand wave topography. We found indications that acoustic techniques can be used to determine the location of epibenthic reefs. The multiscale assessment toolbox furthermore allows formulating recommendations for conservation management related to the impact of sea floor disturbances through dredging and trawling.

    The ecology of wild zebra finch song – why do they sing?
    Loning, Hugo ; Griffith, Simon C. ; Naguib, M. - \ 2020
    In: Wias Annual Conference 2020 WIAS - p. 35 - 35.
    The zebra finch Taeniopygia guttata is the most studied songbird in the lab but the functions of their song in the wild, Australia’s arid zone, remain unclear. Like many songbirds,male zebra finches sing to attract a female. However, unlike the typically studied songbirds,zebra finches are nomadic birds that live in fission-fusion societies. They pair early in life (sometimes <100 days) and have extremely faithful monogamous relations. Nevertheless,males sing throughout their life. So why do zebra finches sing? In this talk I present data collected at Fowlers Gap Arid Zone Research Station in New South Wales, Australia, home of the world’s only nest box breeding population of zebra finches. Using advanced audio recording techniques and standard behavioural observations, I show that zebra finchessing uncharacteristically soft and that they sing in a variety of contexts, such as in groups at social areas. By studying this lab ‘supermodel’ in the wild, where it evolved, this research may bridge the gap between our understanding of this species in the lab and birdsong in general, already one of the best studied model systems for animal communication.
    Debris-flow-dominated sediment transport through a channel network after wildfire
    Nyman, Petter ; Box, Walter A.C. ; Stout, Justin C. ; Sheridan, Gary J. ; Keesstra, Saskia D. ; Lane, Patrick N.J. ; Langhans, Christoph - \ 2020
    Earth Surface Processes and Landforms 45 (2020)5. - ISSN 0197-9337 - p. 1155 - 1167.
    channel network - debris flow - sediment budget - sediment deposition - wildfire

    Field studies that investigate sediment transport between debris-flow-producing headwaters and rivers are uncommon, particularly in forested settings, where debris flows are infrequent and opportunities for collecting data are limited. This study quantifies the volume and composition of sediment deposited in the arterial channel network of a 14-km2 catchment (Washington Creek) that connects small, burned and debris-flow-producing headwaters (<1 km2) with the Ovens River in SE Australia. We construct a sediment budget by combining new data on deposition with a sediment delivery model for post-fire debris flows. Data on deposits were plotted alongside the slope–area curve to examine links between processes, catchment morphometry and geomorphic process domains. The results show that large deposits are concentrated in the proximity of three major channel junctions, which correspond to breaks in channel slope. Hyperconcentrated flows are more prominent towards the catchment outlet, where the slope–area curve indicates a transition from debris flow to fluvial domains. This shift corresponds to a change in efficiency of the flow, determined from the ratio of median grain size to channel slope. Our sediment budget suggests a total sediment efflux from Washington Creek catchment of 61 × 103 m3. There are similar contributions from hillslopes (43 ± 14 × 103 m3), first to third stream order channel (35 ± 12 × 103 m3) and the arterial fourth to fifth stream order channel (31 ± 17 × 103 m3) to the total volume of erosion. Deposition (39 ± 17 × 103 m3) within the arterial channel was higher than erosion (31 ± 17 × 103 m3), which means a net sediment gain of about 8 × 103 m3 in the arterial channel. The ratio of total deposition to total erosion was 0.44. For fines <63 μm, this ratio was much smaller (0.11), which means that fines are preferentially exported. This has important implications for suspended sediment and water quality in downstream rivers.

    Gemeenten negeren afspraken tegen luchtvervuiling en vinden lucht al 'schoon genoeg'
    Krol, Maarten - \ 2020

    Bij veel gemeenten ontbreekt de kennis en menskracht om met dit akkoord aan de slag te gaan

    Maarten Krol, hoogleraar luchtkwaliteit

    Maatregelen zijn schoner vervoer, bouwmachines met minder uitstoot, schonere bedrijven, minder uitstoot door landbouw en minder overlast door houtstook.

    De geringe belangstelling is een gemiste kans, zegt de Wageningse hoogleraar luchtkwaliteit Maarten Krol. De laatste decennia is de luchtkwaliteit in Nederland er flink op vooruit gegaan. ,,Maar er is nog veel winst te halen om de gezondheid van mensen te verbeteren.”

    Maar hij snapt het wel. ,,Bij veel gemeenten ontbreekt de kennis en menskracht om met dit akkoord aan de slag te gaan. En het kost ze geld.”

    ‘Gezonde longen van levensbelang’

    Krol vindt het akkoord een mooi initiatief, maar te vrijblijvend. ,,De regie wordt neergelegd bij provincies en gemeenten, maar de minister kan deelname niet afdwingen.”

    In eerste instantie is het akkoord vooral besproken met grote gemeenten die kampen met extra luchtvervuiling, aldus het ministerie van Infrastructuur en Waterstaat in een reactie. ,,Alle gemeenten kunnen zich later dit jaar alsnog aanmelden en als volwaardige deelnemer meedoen.”

    Optimizing Low–Socioeconomic Status Pregnant Women’s Dietary Intake in the Netherlands: Protocol for a Mixed-Methods Study
    Beulen, Yvette H. ; Geelen, Anouk ; Vries, Jeanne H.M. De; Super, Sabina ; Koelen, Maria A. ; Feskens, Edith J.M. ; Wagemakers, Annemarie - \ 2020
    JMIR Research Protocols 9 (2020)2. - ISSN 1929-0748
    Although the importance of maternal nutrition is evident, adherence to dietary guidelines is limited in pregnant women, especially in those with a low socioeconomic status. Promotion of a healthy diet in midwifery practice is promising, as prenatal diet affects both maternal and child health, pregnant women are open to dietary changes during this critical transition, and midwives are their first and most important source of information. Unfortunately, nutrition communication by Dutch midwives is limited.
    Objective: The objective of this study is to optimize the dietary intake of low–socioeconomic status pregnant women by contributing to the further development and adjustment of a tool or toolbox to support midwives in providing nutrition communication.
    Methods: This interdisciplinary, mixed-methods study includes 2 phases, in which quantitative and qualitative research are complementary. In phase 1, we will conduct a literature study and interviews to gain insight into midwives’ knowledge, needs, and practice. We will obtain data on the dietary intake of low–socioeconomic status pregnant women and factors influencing this intake from another literature study, an interviewer-administered meal-based food frequency questionnaire, and qualitative interviews with pregnant women. We will identify the availability of suitable tools to improve pregnant women’s dietary intake from the literature, interviews, focus groups, and expert meetings. In phase 2, we shall adapt an existing tool or develop a new tool(box), depending on the results of phase 1, and implement it in 5 midwifery practices. Ultimately, a process evaluation will provide insight into barriers and facilitating factors playing a role in the implementation of the tool(box).
    Results: The main outcome of this study will be a tool(box) to optimize the dietary intake of Dutch pregnant women. We anticipate that the developed or adjusted tool(s) will be available in February 2020. After we implement the tool(s) and evaluate the implementation process, the final results should be available by February 2021.
    Conclusions: This study is scientifically and socially relevant, as we will study low–socioeconomic status pregnant women’s contextual dietary intake in-depth from an ecological perspective on health. The results obtained will lead to recommendations for multidisciplinary strategies to promote a healthy maternal dietary intake in low–socioeconomic status populations.
    All sparse PCA models are wrong, but some are useful. Part I: Computation of scores, residuals and explained variance
    Camacho, J. ; Smilde, A.K. ; Saccenti, E. ; Westerhuis, J.A. - \ 2020
    Chemometrics and Intelligent Laboratory Systems 196 (2020). - ISSN 0169-7439
    Explained variance - Exploratory data analysis - Residuals - Scores - Sparse principal component analysis

    Sparse Principal Component Analysis (sPCA) is a popular matrix factorization approach based on Principal Component Analysis (PCA) that combines variance maximization and sparsity with the ultimate goal of improving data interpretation. When moving from PCA to sPCA, there are a number of implications that the practitioner needs to be aware of. A relevant one is that scores and loadings in sPCA may not be orthogonal. For this reason, the traditional way of computing scores, residuals and variance explained that is used in the classical PCA can lead to unexpected properties and therefore incorrect interpretations in sPCA. This also affects how sPCA components should be visualized. In this paper we illustrate this problem both theoretically and numerically using simulations for several state-of-the-art sPCA algorithms, and provide proper computation of the different elements mentioned. We show that sPCA approaches present disparate and limited performance when modeling noise-free, sparse data. In a follow-up paper, we discuss the theoretical properties that lead to this undesired behavior. We title this series of papers after the famous phrase of George Box “All models are wrong, but some are useful” with the same original meaning: sPCA models are only approximations of reality and have structural limitations that should be taken into account by the practitioner, but properly applied they can be useful tools to understand data.

    Breaching the black box: The role of ramps in Thai sustainable palm oil certification
    Innocenti, E. Degli; Oosterveer, P.J.M. ; Mol, A.P.J. - \ 2020
    Asia Pacific Viewpoint 61 (2020)1. - ISSN 1360-7456 - p. 85 - 101.
    palm oil - ramps - Round Table on Sustainable Palm Oil - sustainable value chains - Thailand
    Certification of sustainable palm oil as organised through the Round Table on Sustainable Palm Oil is based on a simplified understanding of the global palm oil value chain – according to which instructions about production practices can be directly translated from the palm oil mill to the primary producer. The reality of palm oil provision is much more complex than this as is shown in the case of Thailand. On the basis of qualitative field study in Southern Thailand this paper clarifies that intermediary stages, such as the collection of oil palm fruit bunches at the ramp, play a key role in the organisation of the chain. The fluidity and complexity of the palm oil flow at the local level complicates the promotion of sustainability through certification. Global and national stakeholders, such as processing and trading firms, non-governmental organisations and national governments, should therefore open this black box of local dynamics to more effectively contribute to sustainability in palm oil supply.
    Relative preference for wooden nests affects nesting behaviour of broiler breeders
    Oever, Anna C.M. van den; Rodenburg, T.B. ; Bolhuis, J.E. ; Ven, Lotte J.F. van de; Hasan, Md Kamrul ; Aerle, Stephanie M.W. van; Kemp, Bas - \ 2020
    Applied Animal Behaviour Science 222 (2020). - ISSN 0168-1591
    Behaviour - Broiler breeder - Nest design - Preference test - Welfare

    Optimising nest design for broiler breeders has benefits for both the animals and the producers. The welfare of the hens will increase by providing preferred housing, while also reducing eggs laid outside the nests. These floor eggs cause economic losses by compromised automatic egg collection and reduced saleability and hatchability. Attractiveness of nests can involve factors such as seclusion, material and microclimate. In this study, four nest box designs were offered in a relative preference test: a plastic control nest, a plastic nest with a partition to divide the nest in two areas, a plastic nest with a ventilator underneath to create air flow inside the nest and a wooden nest. Six groups of 100 hens and 9 roosters had access to these four nests in a randomised location during the ages of 20 to 34 weeks. Nest and floor eggs were collected five days a week. Camera images from inside the nests made during the ages of 24–25 weeks and 26–27 weeks were analysed for behaviour. This included general activity, nest inspections, nest visits and social interactions. At 32 weeks of age the wooden nests were closed, and the subsequent response of the hens was monitored in terms of number of eggs. We found a clear preference in number of eggs for the wooden nest (69.3 ± 1.0%) compared to the control nest (15.1 ± 0.8%), partition nest (10.2 ± 0.5%) and the ventilator nest (5.4 ± 0.4%; p<0.0001 for difference between all nest designs). The preference for the wooden nest was also reflected in an increased time spent sitting, together with fewer nest inspections and visits per egg laid in the wooden nest. The preference for the wooden nest led to crowding, which caused an increased amount of piling, nest displacement, aggression and head shaking. The fact that the hens were willing to accept the crowded circumstances in these nests, underlines the strength of this preference. After the wooden nests were closed, the hens chose a new nest based on a combination of nest design and location. The control nest was still preferred over the other two plastic designs, although the neighbouring nests were overall preferred to the non-neighbouring nests. This study shows how the material used for nests is an important factor in suitability and should therefore be taken into account when designing nests.

    Consultants as intermediaries: Their perceptions on citizen involvement in urban development
    Stapper, E.W. ; Veen, M. Van der; Janssen-Jansen, L.B. - \ 2020
    Environment and Planning C: Politics and Space 38 (2020)1. - ISSN 2399-6544 - p. 60 - 78.
    citizen participation - Consultancy - development agreement - urban development

    Planning consultants are increasingly hired to organize citizen participation processes for urban development projects. However, the ways in which planning consultants engage in and perceive the involvement of citizens in urban development projects remain relatively understudied. This article opens the black box of consultancy employees’ perceptions toward citizens in urban development processes. Employees from two consultancy firms in the Netherlands were interviewed, and several focus groups were organized. This research shows that consultants have wide-ranging views concerning the ways of incorporating citizens’ interests in urban development projects. With the use of Q-methodology, a typology of how consultants engage with citizens is proposed. Furthermore, we show that the different perceptions of consultants lead to a different approach in identifying the needs and problems of citizens. This finding gives insight into the context in which decisions about urban development are made.

    On function monotonicity in simplicial branch and bound
    Hendrix, E.M.T. ; Salmerón, J.M.G. ; Casado, L.G. - \ 2019
    - 5 p.
    Branch and bound methods in Global Optimization guarantee to find the set of global minimum points up to a certain accuracy. Partition sets typically take the shape of boxes, cones and simplices. In the tradition of interval arithmetic for generating bounds on box shaped partition sets, the concept of monotonicity test is used in order to reduce dimension. This paper shows how such a concept can be extended to simplicial partition sets and how to elaborate it for the Standard Quadratic Program.
    Correction to: Molecular characterization of Ecuadorian quinoa (Chenopodium quinoa Willd.) diversity: implications for conservation and breeding
    Salazar, Juan ; Roman, Viviana Jaramillo ; Gutierrez, Bernardo ; Loo, Eibertus Nicolaas van; Lourdes Torres, María de; Torres, Andrés Francisco - \ 2019
    Euphytica 215 (2019)12. - ISSN 0014-2336

    Due to an unfortunate error of miscommunication, two of the co-authors of this manuscript were omitted from the original publication. The correct representation of the authors and their affiliations are listed here and should be treated as definitive. Juan Salazar1, Viviana Jaramillo Roman2, Bernardo Gutierrez1,3, Eibertus Nicolaas van Loo2, Mari´a de Lourdes Torres1, Andre´s Francisco Torres1,2 1. Laboratorio de Biotecnologi´a Vegetal, Colegio de Ciencias Biolo´gicas y Ambientales, Universidad San Francisco de Quito USFQ, Diego de Robles y Vi´a Interocea´nica, Cumbaya´, Ecuador 2. Wageningen UR Plant Breeding, Wageningen University and Research, PO Box 386, 6700 AJ Wageningen, The Netherlands 3. Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK Furthermore, the acknowledgments section has been adapted to match the changes in authorship. The corrected acknowledgements, presented below, are definitive: This research was funded with a Chancellor’s Grant (2015) from Universidad San Francisco de Quito USFQ (Quito-Ecuador). Germplasm access and research permit were granted by the Ministry of Environment of Ecuador (MAE-DNB-CM-2016- 0044). The authors would like to acknowledge the technical assistance offered by researchers at the Plant Biotechnology Laboratory (COCIBA, USFQ), as well as Dr. Leonardo Zurita for his assistance with georeferenced mapping. The authors would also like to acknowledge Dr. Gerard van der Linden (Wageningen University and Research) for supporting our efforts to search and collect quinoa germplasm throughout the Andes of Ecuador.

    WUR: Too Good To Go is effectief instrument tegen voedselverspilling
    Stroosnijder, Sanne ; Haar, Sandra van der; Zeinstra, Gertrude ; Timmermans, Toine - \ 2019
    Darwin's Black Bee Box put in action
    Blacquiere, T. ; Boot, Willem ; Calis, Johan ; Stratum, P. van; Tom, Jolanda ; Pauwel, Rob van - \ 2019
    - 1 p.
    While its native distribution ranges from Western Asia to Africa and Europe, the Western Honeybee Apis mellifera has travelled all over the world with settlers who valued its hive products and pollination service. Introduced in the Netherlands in the 1980’s, the mite Varroa destructor is able to parasitize colonies of Apis mellifera, leading to colony collapse within 3 years in the absence of treatment. It is considered the most serious threat to beekeeping and therefore to agricultural production and food security. As a prevention measure, colonies are constantly managed with acaricides in order to lower mite populations.
    However, continuous control measures prevent the establishment of a balanced host-parasite relationship1. Building on the knowledge gained from examples of populations that developed resistance to Varroa destructor2, we developed a selection protocol based on the principles of Darwin’s evolution by natural selection and compatible with a beekeeping settings3. As the quality of each colony is evaluated on its fitnessrelated properties rather than directly on mechanisms involved in Varroa resistance, we use the image of a black box from which the in and outputs are known but the mechanism remains hidden4.
    On the verge : Mechanics in the limit of vanishing strength and stiffness
    Doorn, Jan Maarten van - \ 2019
    Wageningen University. Promotor(en): J. van der Gucht, co-promotor(en): J. Sprakel. - Wageningen : Wageningen University - ISBN 9789463950329 - 249

    Material mechanics play a crucial role in a wide variety of scenarios and applications. Here we focused on two central material properties: stiffness and strength. Whereas stiffness characterizes the resistance to deformation for small strains, where the response remains linear, strength describes the resilience of a material to larger deformations and mechanical damage. For conventional materials strength and stiffness are readily described by established mechanical theories. However, many materials in nature, or engineering materials during processing, live in a state where stiffness and/or strength becomes so weak that classical mechanical theories no longer apply. This has been the focal point of this thesis. The exploration of such ultrasoft and/or ultraweak solids faces many challenges, some of which have been addressed in this thesis, including their structure-property relationships and the question howone characterizes these fragile materials where conventional mechanical methods are no longer viable. In chapter 2 we address the challenge of characterizing the mechanical response of solids at the verge of a mechanical instability, where classical approaches fail. We present a new method based on the propagation of infrasonic waves. These waves propagate at low Reynolds numbers, where dissipation is strong. We have not only shown an experimental approach to evaluate wave propagation properties, but also established a theoretical framework to interpret these data and extract quantitative mechanical properties with a unique resolution. In chapter 3 we detail the technical challenges associated with these measurements, performed with the help of optical tweezers to create travelling mechanical waves. When marginal networks are combined with secondary elastic matrices remarkable stiffening is observed. In chapter 4 we present a theoretical model to study the effect of bending rigidity to the mechanics in hybrid materials with simulations. We show how different mechanical regimes arise depending on the bending stiffness and the stiffness of the secondary network. Each of these regimes have different mechanisms that lead to mechanical enhancement of the composite network. Experimental access to these mechanisms is extremely challenging. In chapter 5 we take the first steps to studying these mechanisms experimentally. Here we propose a simple click-chemistry based surface modification method that can help to achieve the complex inter-particle interactions required for establishing hybrid colloidal networks. The second part of this thesis covers hyperweak solids and irreversible deformation. Chapters 6 to 8 deal with colloidal gels that are prototypical examples of hyper weak solids. In chapter 6 we address the structure to dynamics part of the structure-property relation in colloidal gels. We experimentally establish the connection between the intermittent dynamics of individual particles and their local connectivity. We interpret our experimental results with a model that describes single-particle dynamics based on highly cooperative thermal debonding. Our model is in quantitative agreement with experiments and provides a microscopic picture for the structural origin of dynamical heterogeneity and provides a new perspective of the link between structure and the complex mechanics of these heterogeneous solids. Chapter 7 focuses on the dynamics to mechanics part of the structure-property relation by studying fatigue in colloidal gels. Here we combine experiments and computer simulations to show how mechanical loading leads to irreversible strand stretching, which builds slack into the network that softens the solid at small strains and causes strain hardening at larger deformations. We thus find that microscopic plasticity governs fatigue at much larger scales. This sheds new light on fatigue in soft thermal solids and calls for new theoretical descriptions of soft gel mechanics in which local plasticity is taken into account. In chapter 8 we take first steps in investigating the overlooked role of inter-particle friction in colloidal gels. We present a colloidal system with a thermo-responsive trigger for systematically studying the effect of surface properties, grafting density and chain length, on the particle dynamics within colloidal gels. Microscopically, for colloids with a lower grafting density, we observe an increase in the thermal bond angle fluctuations of aggregated colloids. Macroscopically, we observe a clear increase of the linear elastic modulus for gels with increased grafting density and longer chain lengths. These effects are inversely proportional to the magnitude of local bond angle fluctuations. Our model system will allow for further study of the microscopic origins of the complex macroscopic mechanical behavior of hyperweak solids that include bending modes within the network. Fracture and mechanical failure are highly stochastic processes and predicting fracture is highly challenging with conventional theories but crucial to assessing the lifetimes of e.g. buildings, bridges and implants. In chapter 9 we explore new opportunities for predicting fracture in marginal fiber networks. Fracture is the ultimate form of irreversible deformation and, especially in soft materials, characterized with highly non-linear mechanics preempting the moment of failure. We show how machine learning methods can by employed to predict the critical fracture stress solely based on structural and topological input parameters. We show that neural networks, despite their black box behavior, can be used to study the physical mechanisms underlying fracture. By varying the input parameters for our fracture stress predictions we found three parameters for which we can achieve the same prediction quality as for all tested input parameters combined. In the last chapter, the general discussion, we discuss how our results relate to each other and how they fit in a broader context. Furthermore we suggest and describe experiments that can help advance our knowledge of hypersoft and hyperweak materials in the future.

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